JasonZ-YA

iTrader: (60)

yup...........

-J

Z1 Performance

iTrader: (564)

That noise is absolutely, 100% normal

3rd gear at 1500 rpm? You are asking the engine to do quite a lot at this point, and as such, the noise will be there. Drop down to 2nd, like you should be, and you'll suddenly be beyond the rpm point where the noise is present. Not only do you no longer have the benefit of the interia of the heavy flywheel but you're also now not using the factory dual mass unit as mentioned. As such, you now must adjust your driving style a bit, giving it a touch more gas when engaging 1st gear from a dead stop, and not lugging the engine around in low rpm's at high gears. Practice makes perfect

marra23

iTrader: (8)

misted this one i just posted on this, hate the noise
https://my350z.com/forum/forced-indu...ml#post7581473

mx594

iTrader: (4)

I know the noise is normal and I was expecting to hear it, I just wasn't expecting it to be so loud. Nor was I expecting to be able to feel the vibration so much. I drove my coworkers G35 yesterday, he has a Fidanza flywheel / FX400 clutch, as well as a Procharger with HKS exhaust and longtube headers. I tried the same scenario with his car, 1500 rpm in 3rd gear ~75% throttle and the noise was definitely there, although I could just barely make it out over the sound of his exhaust and/or supercharger! I think part of the reason why it's so noticeable in my car is that I have a Greddy Evo2 with stock cats and stock headers, which is almost as quiet as stock.

I have been driving the car for a few days now, and I already find myself downshifting around corners where I never used to before, just to avoid the noise. It's pretty embarrasing to be driving such a nice car and then to have it make that godawful noise all of a sudden. I also have a 3.90 rear end, so I start in 2nd gear quite often. I will probably be starting in first more now, to avoid the noise.

And as far as the dual mass stock flywheel goes, I am well aware of this design feature and it's purpose. Dynamic systems theory tells me that the stock flywheel is really designed in such a way to reduce vibration. Afterall, something has to vibrate to generate noise! To me it sounds like the ACT flywheel is hitting a resonant frequency, and causing a severe vibration that (in my opinion) could be harmful to drivetrain components. It's likely that the dual mass flywheel is designed to change the dampening ratio of the system and as such, change the resonant frequency to something outside of the normal operating frequency (rpm) range of the engine.

I think that the next time I have the tranny out, I will be going back to the stock flywheel.

Z1 Performance

iTrader: (564)

The noises are already there, and they are from the transmission, not the flywheel. The stock flywheel, being heavier and of a dual mass design, simply does a better job of dampening those noises vs any lightweight one ever will.

The ACT is actually better balanced than the factory flywheel, at least the few that I have checked

The noises are all well documented - just a matter of personal preference whether or not it is worth it on an individual basis.